1. Field of the Invention
The present invention relates to an optical disc drive apparatus which can record a signal, and a signal recording method of the same.
2. Description of the Related Art
In recent years, writable optical discs such as CD±R, DVD±R, DVD±RW, and Blu-ray disc are commercially available. In an optical disc apparatus which can meet these optical discs, for example, there is an optical disc apparatus (for example, see Patent Reference 1) which sets a skew target value based on the signal level of an RF playback signal acquired in signal recording to perform skew control (or, it is referred to as tilt control, but hereinafter, it is referred to as tilt because they have the same meanings). However, the RF signal level (the level of a light reflecting from a pit) in the section for detection during recording is varied not only by the change in the tilt angle but also by irregularities in a recording film and temperature change. More specifically, even though the disc is written at the same recording power, the pit is not formed in the same shape because of irregularities in the recording film and temperature change.
In order to solve such problems, under present circumstances, a technique is generally used which is called running OPC (Optimum Power. Control) (hereinafter, it is referred to as ROPC) (for example, see Patent Reference 2). In an ROPC system, the laser recording power is controlled in real time by monitoring the level of a reflecting light so that the level of the reflecting light is made constant. More specifically, for example, suppose a disc is written at a certain level of recording power, or a certain level of multi-pulse power. In the midway of the process, when it is detected that the level of the reflecting light is dropped, which is caused by irregularities in the recording film, for example, the ROPC system performs control so that the recording power is reduced because the pit shape is too deep.
Patent Reference 1: JP-A-2000-331364 (Paragraph [0054] and FIG. 4)
Patent Reference 2: JP-A-2002-288831 (Paragraph [0008])